Abstract
Tumour antigen-induced inhibition of leucocyte adherence was modified for use in glass test tubes (Tube LAI assay) for the study of cell-mediated anti-tumour immunity to human malignant melanoma. Peripheral blood leucocytes (PBL) of 20 out of 25 patients (80%) with active malignant melanoma responded to an extract of malignant melanoma with LAI, whereas only 4-5% of 475 control subjects showed a response. The malignant melanoma patients reacted to both allogeneic and autologous extracts of malignant melanoma which indicates a common cross-reacting antigen. Malignant melanoma patients did not respond to unrelated tumour extracts. The LAI was mediated by PBL (monocytes) "armed" with cytophilic anti-tumour antibody specific for the sensitizing tumour antigen. The anti-tumour response of the malignant melanoma patients was dependent on the stage of the cancer, and 11 out of 13 Stage I patients had a positive NAI, whereas patients with disseminated cancer had decreased response. The diminished LAI in patients with large tumour burdens appeared to be the result of release of tumour antigen systemically. Also, surgery and chemotherapy depressed LAI. Although LAI was depressed after surgical excision of the cutaneous melanoma, most patients showed LAI 1-3 months later. Tumour-free melanoma patients monitored for one year by the Tube LAI assay showed a decline in their anti-tumour immunity 5-6 months after surgery. The NAI was low or negative after the 8th post-surgical month in tumour-free patients. Patients with residual malignant melanoma showed persistent or recurrent LAI after the 8th post-surgical month. LAI reactivity monitored after "curative" surgery for malignant melanoma may assist in determining whether the patient is tumour-free or has a recurrence.
Highlights
(PBL) of 20 out of 25 patients (80%) with active malignant melanoma responded to an extract of malignant melanoma with leucocyte adherence inhibition (LAI), whereas only 4.5%o of 475 control subjects showed a response
In the amounts of the tumours were taken for present study we show that LAI depends routine pathology
Specificity of LAI in test tubes When PBL from malignant melanoma patients or control subjects are incubated in glass test tubes without antigen for 2 h, generally less than 10% of the cells are non-adherent
Summary
Subject studies-.Heparinized melanoma, breast cancer, and other tumours were 6-8-5 mg/ml. Incubation of the cells in the absence of tumour extract beyond a 2-h period did not produce appreciably increased adherence of leucocytes to glass. The stock tumour extracts were diluted and added to the test tubes at different protein concentrations. Other tumour extracts were used at approximately 100 ,ug protein/test tube. At the end of this period, the cells were spun dow,n, washed 3 times with Medium 199 and plated separately in test tubes with Medium 199 alone, breast cancer and melanoma extracts. PBL from healthy subjects were tested in the LAI assay after incubation with 199 alone, with serum from control subjects and from patients with metastatic disease who were non-reactive. Thie purity of the isolated IgG was examined by immunoelectrophoresis with anti-wholehuman serum
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